As is known the so-called BMA (hydrocyanic acid-methane-ammonia) process for the production of hydrogen cyanide or hydrocyanic acid starts from methane and ammonia and operates without the presence of oxygen or air.
The reaction itself is carried out in suspended reaction tubes of aluminum oxide which are coated on the inside with a platinum catalyst.
Since the reaction proceeds endothermally the reaction tube is heated and thereby reaction temperatures of around 1300.degree. C. are maintained. In order to avoid the occurrence of reverse reaction the hydrogen cyanide containing gas mixture formed must be quickly cooled to temperatures below 400.degree. to 300.degree. C., which takes place in a water cooled chamber made of aluminum in the reactor head itself, see Ullman Enzyklopadie der technischen Chemie, 4th edition Vol. 9, page 659; Dechema-Monographic, 1959, Vol. 33, pages 28 to 46 and also German patent 959,364 and related Endler U.S. Pat. No. 2,987,383.
While in using pure methane as the hydrocarbon generally there are not observed any disturbing deposits of carbon black there do occur disturbances when using types of natural gas which contain only a few percent of ethane and propane. In employing these gases the catalyst began to be fouled with soot, specifically in such an amount that the operation of the sooted reaction tube must be stopped, see Belgian Pat. No. 828,647.
Sooting occurs especially in experiments to produce hydrogen cyanide directly with propane or butane and ammonia.
Although the use of the most highly pure methane has been found to be very desirable for carrying out the hydrocyanic acid-methane-ammonia process, yet the industrial operation was completely dependent upon the presence of the most highly pure methane and thus tied to the location of the methane.
The purpose of the process of the invention is the carrying out of the hydrocarbon-ammonia reaction to form hydrogen cyanide using a hydrocarbon different from methane and namely in such a way that there is avoided the deposition of carbon black and therewith disturbances in operation.